Synonyms for Heavy:

adj.

close (adjective)
muggy.
depressed, gloomy (adjective)
sodden, lowering, soggy, dejected, sad, leaden, overcast, sorrowful, melancholy, dull, damp, dismal, wet, cloudy.
difficult, severe (adjective)
intolerable, harsh, complicated, troublesome, stormy, knotty, arduous, recondite, tempestuous, effortful, abstruse, toilsome, violent, oppressive, confused, profound, vexatious, grievous, wild, formidable, laborious, labored, rough, grave, complex, turbulent, hard, esoteric, onerous.
dull (adjective)
listless, indifferent, apathetic, lumpy.
effortful (adjective)
effortful.
generous (adjective)
plenteous, plenitudinous.
gray (adjective)
leaden.
having great weight (adjective)
considerable, elephantine, lumbering, huge, substantial, ample, bulky, cumbrous, portly, burdensome, built, weighty, stout, loaded, copious, overweight, awkward, laden, fleshy, beefy, unwieldy, big, weighted, fat, ponderous, cumbersome, abundant, top-heavy, massive, chunky, hefty.
heavy (adjective)
leaden, massive, ponderous, dense, pressing, weighty, gravitational, oppressive.
hot-blooded (adjective)
red hot.
insensitive (adjective)
dull.
large (adjective)
massive.
listless, slow (adjective)
apathetic, indifferent.
loud (adjective)
tumultuous.
lumbering (adjective)
heavy-footed.
overweight (adjective)
fleshy, fat, stout.
rough (adjective)
roiled.
sensuous (adjective)
sultry.
strong (adjective)
heavy-duty.
thick (adjective)
gelatinous.
threatening (adjective)
lowering.

adv.

all (adverb)
heavily.

n.

best, A-LINE, boot-cut, button-down, brief, Clingy, casual, backless, button-through, baggy. enormous, considerable, extensive, widely, troublesome. convulsive, be all fingers and thumbs, jerky, robotic, go slowly, ungainly, be tedious, uncoordinated, wooden, clumsy, drag, awkward. agonising, burning, chronic, agonizing, crippling, achy, chapped, angry, bad. bulky, hulking, husky, desperate, stout, awful, hulky, dire, extreme. bountiful, generous, celebratory, plenitudinous, rich, frugal, substantial, ample, give, set, satisfying, plenteous, abundant, alfresco, slap-up, plentiful, voluminous, sit down, copious, hearty, bounteous. chalky, Heightened, flinty, marshy, pebbly, intense, peaty, hardscrabble, intensive, boggy, fierce, alluvial. powerful, be an effort. automatically, high, broken, clockwork, furious, clean, cordless, built, clever, automatic, auxiliary, analog. excess, a force to be reckoned with, leading light, prime mover, two-fisted, mogul, vip, magnate, mover and shaker, eminence, figure, authority figure. bodyguard, momentous, caretaker, earnest, gatekeeper, custodian, gamekeeper, concierge, doorkeeper, beefeater, bruiser, attack dog. congested, gelatinous, bulging, teeming, stodgy, busy, crowded, cramped, solid, packed, jammed. broadsheet, ingestion, back copy, bulletin, brochure, comic book, comic, back-number, back issue, biweekly. heavy-laden, low, plangent, hollow, resonant, bass, low-pitched, laden, loaded. exigent, exacting, bloodshot, dead, rigorous, formidable, clear, bug-eyed, trying, cross-eyed, beady, doe-eyed, deep-set, hazel, demanding, close-set. choppy, fresh, right, coastal, villain, briny, freshwater, deep-sea, fluvial. calorific, cream, crispy, chewy, caramelized, buttery, crisp, chilled, cool. delicate, thorny, impossible, critical, intractable, intolerable. strange, unsettling, tight, claustrophobic, unnatural, uncomfortable. full on the mouth/chin etc., mightily, lightly, fiercely. inclement, unseasonable, muggy, humid, sultry, raw. redolent, odorous, odorless, odoriferous. burdensome (noun)
troublesome, vexatious.
gloomy (noun)
sad, overcast, dismal, dejected.
heavy (noun)
dull, clayey, sullen, accented, deep, backbreaking, laboured, full, taxing, harsh, welterweight, labored, heavy-footed, grievous, dense, leaden, laborious, heavy-duty, cloudy, profound, massive, toilsome, soggy, distressful, steep, wide, labourious, fat, compact, middleweight, burdensome, grueling, overweight, worrisome, impenetrable, grave, weighed down, broad, perturbing, heavily, onerous, sonorous, big, of import, sound, gruelling, indigestible, disturbing, hard, ponderous, heavyweight, wicked, weighted, important, wakeless, punishing, weighty, thick, threatening, troubling, lumbering, arduous, hefty, lowering, distressing, cloggy, intemperate, stressed, fleshy, strong, oppressive, doughy, effortful, worrying.
soggy (noun)
wet, sodden, inedible, damp.
viscous (noun)
viscid.

Other synonyms:

earnest, hearty, top-heavy, esoteric, momentous, lush, luxuriant, hardscrabble, freshwater, gelatinous, long-range, trying, abstruse, demanding, coastal, fiercely, intensive, tempestuous, powerful, redolent, lumpy, roiled, mightily, raging, laden, turbulent, stout, hulking, counterweight, nuclear, cramped, alfresco, density, profuse, rich. copious, loaded, stormy, claustrophobic, lumpish, conventional, plentiful, abundant, rigorous, roily, tumultuous, strange, intense, uncomfortable, dead weight, exigent, stodgy. voluminous, exacting, substantial, ample, unnatural, furious, dirty. formidable, load, surface, generous, ugly, fierce, rugged, hollow, live. rough, bass, violent. lightly. fresh. wild. net, set. tight. high. low. awkward
unwieldy.
big
big.
fat
fat, portly.
inconvenient
awkward.
laborious
laborious.
massive
bulky.
Other relevant words:
dull, fat, accented, awkward, grievous, elephantine, heavyweight, stout, steep, arduous, listless, low-pitched, bulky, heavily, hard, burdensome, big, sad, strong, overweight, grave, dead, hefty, dirty, wooden, dense, thick, stodgy, stressed, onerous, cloudy, compact, laden, lumpish, fleshy, deep, low.

Usage examples for heavy

  1. " Oh it is with a heavy heart, sir; and I shall always remember your kindness. – Put Yourself in His Place by Charles Reade